title: Indolylacetic acid and N6-(delta 2-isopentenyl) adenine affect NADH binding to yeast alcohol dehydrogenase and inhibit in vitro the enzymatic oxidation of ethanol.
abstract: Derivative UV spectroscopic data show that the plant growth substances N6-(delta 2-isopentenyl) adenine (i6Ade) and indolylacetic acid (IAA) can bind to the yeast alcohol dehydrogenase (ADH) and affect coenzyme-enzyme binding. This is confirmed by enzyme kinetics studies. At fixed ethanol concentrations (27.8 and 111.1 mM) and varying NAD+ concentrations (0.033-2 mM), as well as at fixed levels of coenzyme (0.67 and 2 mM), and at varying concentrations of ethanol (1.4-111.1 mM), the rate of ethanol oxidation is significantly inhibited by i6Ade and IAA. The kinetics of the ADH reaction is affected by two inhibition constants (KI and K'I) which correspond to the dissociation constants of complexes EI and ESI, respectively. For i6Ade the KI = 0.52 +/- 0.06 mM and K'I = 0.74 +/- 0.07 mM, and for IAA the KI = 0.88 +/- 0.03 mM and K'I = 0.99 +/- 0.02 mM.
authors.affiliation: August Kirchenstein Institute of Microbiology, Latvian Academy of Sciences, Ríga, USSR.
authors.forename: P
authors.initials: P
authors.lastname: Zikmanis
authors.forename: R
authors.initials: R
authors.lastname: Krüce
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000426:Alcohol Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D003627:Data Interpretation, Statistical; D000431:Ethanol / Q000378:metabolism*; D007210:Indoleacetic Acids / Q000494:pharmacology*; D007541:Isopentenyladenosine; D007700:Kinetics; D009243:NAD / Q000378:metabolism*; D010084:Oxidation-Reduction; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013056:Spectrophotometry, Ultraviolet
chemical_list: D007210:Indoleacetic Acids; D009243:NAD; C001478:N(6)-(delta(2)-isopentenyl)adenine; D000431:Ethanol; C030737:indoleacetic acid; D007541:Isopentenyladenosine; D000426:Alcohol Dehydrogenase; D000225:Adenine